What was the average daily expenditure in $Rs.$ of a man in $1999$ who spent $Rs. \, 76535$ in the first half of the year and $Rs. \, 88165$ in the second half?

The average age of a group of $18$ persons is $32$ $years$ and $6$ $months$. If two persons of age $65$ $years$ each and one person of age $50$ $years$ leave the group,the average age of the remaining persons in the group will be (in $years$)

The average salary per head of all workers of an institution is $Rs. 60$. The average salary per head of $12$ officers is $Rs. 400$. The average salary per head of the rest is $Rs. 56$. Then,the total number of workers in the institution is?

Average age of $A, B$ and $C$ is $84 \text{ years}$. When $D$ joins them,the average age becomes $80 \text{ years}$. $A$ new person,$E$,whose age is $4 \text{ years}$ more than $D$,replaces $A$ and the average of $B, C, D$ and $E$ becomes $78 \text{ years}$. What is the age of $A$ (in $\text{years}$)?

The average age of students of a class is $15.8 \text{ years}$. The average age of boys in the class is $16.4 \text{ years}$ and that of the girls is $15.4 \text{ years}$. The ratio of the number of boys to the number of girls in the class is:

If the average of $x$ and $\frac{1}{x} (x \neq 0)$ is $M$,then the average of $x^{2}$ and $\frac{1}{x^{2}}$ is